Over the years, many kinds of leg prostheses have been devised in effort to replace the leg or legs that amputees have lost. All these leg prostheses have the difficult task of giving to these amputees a gait as normal as possible. The complexity of human locomotion, however, is such that conventional leg prostheses have until now only been using passive mechanisms where the “computerized” passive leg prosthesis are considered on the market as the most sophisticated available devices. Conventional leg prostheses are very limited compared to a real human leg and some needs were thus not entirely fulfilled by them.
According to amputees, specific conditions of use of conventional leg prostheses, such as repetitive movements, continuous loading and assisted mobility from the amputee, typically entail problems such as increases in metabolic energy expenditures, increases of socket pressure, limitations of locomotion speeds, discrepancies in the locomotion movements, disruptions of postural balance, disruptions of the pelvis-spinal column alignment, and increases in the use of postural clinical rehabilitation programs.
Another problem is that during the amputees' locomotion, energy used for moving the prosthesis mainly originates from the amputees themselves because conventional leg prostheses do not have self-propulsion capabilities. This has considerable short and long-term negative side effects. Recent developments in the field of energy-saving prosthetic components have partially contributed to improve the energy transfer between the amputees and their prosthesis. Nevertheless, the problem of energy expenditure is still not fully resolved and remains a major concern in the field of prosthesis and orthosis.
The difficulty related to the development of such complex leg prostheses design is compounded by the lack of testing equipment that realistically simulate human locomotion. The use of such testing equipment would allow the designers to perfect the leg prosthesis at early design stages. As well, a human locomotion simulator would permit, throughout the development, to test efficiently in controlled conditions the performance of prosthesis in various conditions such as walking, running, ascending or descending stairs, for example. Moreover, the use of such simulator means that the whole development and the perfecting of leg prosthesis is carried out without clinical trials with humans; which is benefic in terms of security. Furthermore, without limiting to this specific application, such testing equipment could be used also to test footwear to simulate more realistic environment of use.
Considering this background, it clearly appears that there was a need to develop a human locomotion simulator for the simulation of various types of gaits.